TORONTO — His single piece of advice to then premier Dalton McGuinty when he was deciding to cancel the construction of gas plants in Mississauga and Oakville was “whatever you want to do,” his former chief of staff said Tuesday.

Don Guy, Dalton McGuinty’s former chief of staff and the chair of three Liberal election campaigns, repeated the former premier’s assertion that McGuinty acted alone in relocating the two controversial plants at a reported cost of at least $585 million.

The decision was consistent with McGuinty’s tendency to follow “his inner star,” Guy said under oath at a justice committee hearing on Tuesday morning.

Guy, one of the most powerful unelected players in Ontario politics, said his only role was drafting an announcement of the decision, which was made by Liberal Charles Sousa, now Ontario’s finance minister.

Guy told reporters outside a Queen’s Park meeting room that his single piece of advice to Mr. McGuinty was, “whatever you want to do.” He noted that McGuinty made a commitment as Liberal leader to scrap the partially built Mississauga plant two weeks before election day in October, 2011.

But opposition MPPs were skeptical that such a “skilled and capable” campaign strategist would be relegated to “messenger boy status” during decision making that saw the two partially built plants cancelled days before the 2011 provincial election.

Opposition parties have decried the cancellations as a costly attempt at retaining seats in the legislature, allegations that Mr. Guy dismissed as “search and destroy” politics on Tuesday morning.

Guy said he had no discussions with McGuinty about scrapping the Oakville gas plant, and only discussed the Mississauga project with him after the premier had already made his decision to cancel it.

The opposition parties are fuming that they can’t ask Guy about emails showing he and other unelected Liberals tried to pressure the Speaker into changing a preliminary finding of contempt against the government.

Speaker needs to follow up on his prima facie finding and change his mind

It came after the government failed to release all documents on the gas plants as requested by a legislative committee.

“Speaker needs to follow up on his prima facie finding and change his mind,” Guy wrote last September to senior Liberals including Brendan McGuinty, the premier’s brother and a key part of his campaign team.

The Progressive Conservatives and New Democrats accuse the Liberal chair of the committee of trying to block them from getting to the bottom of the gas plant scandal, and say they have a right to ask about all documents they have been given.

They say Premier Kathleen Wynne promised to be open and transparent about the gas plants and to allow the committee to ask any questions its members want.

The opposition parties say the Liberals spent at least $585-million to cancel the gas plants in order to save Liberal seats in the 2011 election.

The auditor general is scheduled to release a report into the actual cost of cancelling the Oakville gas plant at the end of this month, which most observers predict will send the total bill soaring much higher.

The government has said scrapping the Oakville project cost about $40 million, but the Ontario Power Authority puts the figure at closer to $310 million.

The auditor’s report on the Mississauga gas plant concluded halting the project in mid construction cost $275 million, far above the $190 million that the Liberals had been claiming.